1. Field of Invention
This invention relates to cycles, such as a bicycle, tricycle, motorcycle. More specifically, this invention relates to a recumbent bicycle. Even more specifically, this invention relates to a recumbent bicycle that uses a linearly drive to convert rotary pedal motion to linearly reciprocating pedal motion and with pedals positioned approximately above and on either side of the front wheel to create a short wheel base recumbent bicycle with the seat at or behind the center of gravity for stability. Even more particularly, this invention relates to a recumbent bicycle with an uniquely aligned linear drive that will eliminate crank kickbacks or crank getting stuck during use for a smooth operating linear drive recumbent bicycle. 2. Description of Prior Art
Heretofore, recumbent bicycles are known in prior art and one typical embodiment of bicycles of this type is disclosed in U.S. Pat. Nos. 4,878,684 (E. W. Lemle, November 1989). As is clear from the prior art, it is desirable to construct a recumbent bicycle with an adjustable seat whose position is low with respect to the ground and with pedals located in front of the seat. Both seat and pedals are positioned along the frame of the bicycle. However, recumbent bicycle as illustrated in the foregoing reference have a wheel base that is substantially longer than conventional upright bicycles. Its subsequent weight and length make them slow and hard to maneuverable in tight places. Therefore, it is desirable that the wheel base of a recumbent bicycle be much shorter. To achieve a short wheel base, it is desirable for recumbent bicycles to have linearly reciprocating pedals of my invention so that the crank can remain low between the two wheels and not have to be moved very high up above the front wheel or moved in front of the front wheel.
The closest series of prior arts are disclosed in the SAE Technical paper Series 840021 called the "Evolution of Recumbent Bicycles and the Design of the Avatar Bluebell" by Dr. David Gordon Wilson of the Massachusetts Institute of Technology. The MacMillan Velocipede of about 1839 shown in FIG. 1 on page 1 uses a linear drive but the pedal-sliders interfere with the higher amplitudes of front-wheel steering movements. Also, its crank was connected directly to the axle giving it only one speed, thus making it too strenuous to ride. So, my invention modernizes the structure of the MacMillan Velocipede and made it work.
The second diagram of FIG. 15 on page 6 of the aforementioned technical paper shows a linear drive mechanism very similar to both my invention and the MacMillan Velocipede but differs in structure and have many disadvantages. And the author mentioned the disadvantages of his invention in the paragraph above and below the diagram. First, his pedal-sliders had to be long and curved to fulfill its intended purpose of shortening the wheel base. Since the pedal-sliders have to be strong enough to withstand high pedaling forces, his pedal-sliders design "weight far more . . . than the pedal that it replaced". This is due to the way that the pedal-sliders are attached to the frame. The advantage of my invention is that it allows the use of straight and much shorter pedal-sliders to cut weight. Further, the pedal-sliders of my invention can also be moved forward without extending the length of the pedal-sliders as in this prior art. This allows the accommodation of very long legged people.
Although the first paragraph on page 7 of the prior art had mentioned that the pedal's linear motion axis does not pass through the crank axis giving it a "quick-return motion". But it did not disclose in detail what it means or perhaps did not further investigate its unobvious advantage. The unobvious advantage of not having the pedal's linear motion axis pass through the axis of the crank had been known in piston engine design. So, this prior art did not invent this. And no other prior art explains this principle which prevents the bicycle crank from kicking back or getting stuck when used with a linear drive mechanism.
Therefore, the prior art of the above two paragraph had a structure that is not practical. In addition, it did not describe how and why will the advantage of not having the pedal's linear motion axis passing through the axis of the crank benefit it.